Knee Joint Gap Balancer with Force Sensor
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Solution Overview
Problem
Current gap balancing techniques for total knee arthroplasty are complex and difficult to execute, as they cannot balance the knee joint with the patella in place and require large, cumbersome devices that are specific to each knee system, lacking the ability to measure ligament tension throughout the range of knee motion.
Innovation Solution
A gap balancer device with a tibial interface surface, an opposed femoral interface surface, and at least one force sensor, capable of measuring gap distance, angle, loads, and deflections, and optionally applying a load to distract the joint, allowing for the evaluation and balancing of the knee joint without making a tibial plateau cut.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional gap balancing devices are used, then gap balancing can be achieved, but the devices are large and cumbersome requiring complex procedures
Solution Approach 1:
The gap balancer is divided into separate modular components: a distraction element, a first interface element for the femur, and a second interface element for the tibia. This segmentation allows each component to be optimized independently and enables the device to be assembled and configured for specific surgical needs, reducing overall complexity while maintaining functionality.
Solution Approach 2:
The gap balancer is designed with universal interface elements that can accommodate different bone geometries and knee joint configurations. The distraction element can be adjusted to work with various femoral and tibial cuts, making the device applicable to multiple surgical scenarios without requiring system-specific instrumentation for each knee system.
2Adaptability or versatility
If traditional gap balancing is performed without patella in place, then gap measurement is simplified, but the patella cannot be balanced with the joint
Solution Approach 1:
The gap balancer is inserted into the knee joint before the tibial cut is made, allowing the patella to remain in its anatomical position throughout the balancing process. This preliminary insertion enables the device to measure and balance gaps while the patella is still in place, and the balancer can be removed after balancing without requiring the patella to be displaced or repositioned.
3Measurement precision
If gap balancing is done without measuring ligament tension throughout range of motion, then the procedure is simpler, but accurate ligament tension data is not obtained
Solution Approach 1:
The gap balancer incorporates sensors that continuously monitor and feedback ligament tension data throughout the range of motion. The sensor array detects forces and moments generated by the ligaments as the knee moves through flexion and extension, providing real-time tension measurements that feed back to the surgeon for accurate gap balancing decisions.
Solution Approach 2:
Traditional mechanical measurement methods are replaced with sensor-based detection systems. The sensor array uses electronic sensing to measure ligament tension, replacing complex mechanical measurement apparatus and enabling more precise, continuous data collection throughout the range of motion without adding significant procedural complexity.
4Ease of operation
If tibial plateau cut is made before gap balancing, then gap measurement surfaces are created, but the joint cannot be balanced with patella in place
Solution Approach 1:
The gap balancer is inserted into the knee joint before the tibial cut is made, allowing the patella to remain in its anatomical position throughout the balancing process. This preliminary insertion enables the device to measure and balance gaps while the patella is still in place, and the balancer can be removed after balancing without requiring the patella to be displaced or repositioned.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise measurement and balancing of the knee joint, allowing for accurate digital geometric modeling, and facilitates more efficient and effective total knee arthroplasty procedures by maintaining the patella in place and using a compact, versatile device.
Implementation Method 1
at least one force sensor... capable of measuring gap distance, angle, loads, and deflections
Data Source
AI summary
A method of evaluating a human knee joint which includes a femur bone, a tibia bone, a patella bone, a patellar tendon, and ligaments, wherein the ligaments and patellar tendon are under anatomical tension to connect the femur and tibia together, creating a load-bearing articulating joint, the method including: inserting into the knee joint a gap balancer that includes a tibial interface surface, an opposed femoral interface surface, and at least one force sensor, the method including: providing an electronic receiving device; moving the knee joint through at least a portion of its range of motion; while moving the knee joint, using the electronic receiving device to collect data from the at least one force sensor; processing the collected data to produce a digital geometric model of at least a portion of the knee joint; and storing the digital geometric model for further use.